The proposed research deals with the hypothesis that dreaming sleep is, under specific conditions, adaptive (promoting positive changes in mood and performance). Specific objects include: (a) Investigation of conditions that promote incorporation of (preoccupation with) presleep tasks or problems into ongoing REM dreams, and the association of types and temporal position of incorporation with degree of improvement in performance from presleep to postsleep under conditions of high motivation. (b) Investigation of the changes during the night in the prominence of dream categories related to left and right cerebral hemisphere, and development of possible implications of such changes for a hypothesis about cortical specialization during sleep. (c) Investigation of differential REM sleep requirement for different personalities and its possible implication for understanding the relationship between dreaming sleep and depression. (d) Investigation of the relaionship between differences in initial REM onset latency and personaity, and the therapeutic effect of REM deprivation for depression. Each of these objectives is based on empirical research data obtained by the investigator and by others.